1. Field of the Invention
The present invention relates to image pickup apparatuses and mobile phones, and in particular it relates to a small-sized image pickup apparatus and mobile phone capable of achieving a high-quality imaging function with low cost.
2. Description of the Related Art
Recently, a small-sized thin image pickup apparatus has been widely used so as to be mounted on a small portable electronic instrument such as a mobile phone and a PDA (personal digital assistant). As a result, not only speech information but also image information can be simply transmitted.
In such an image pickup apparatus built in a small portable electronic instrument, because of its small size, a focal length of an imaging optical system is extremely reduced, and the aperture F-value may be set at about 2 to 4 for increasing a shutter speed so as to prevent camera shake. Hence, the depth of focus on the image side is extremely reduced, so that the accuracy in positioning the imaging optical system in the optical axial direction relative to an imaging plane is severely demanded.
Elements on the light receiving section of an image pickup device for photo-electric conversion in the image pickup apparatus are arranged at a pitch of several micro-meters. Thereby, even if a miniature body, such as dust, exists on the image pickup apparatus, an object luminous flux is shielded, impairing picking up object images, so that dust proof of the image pickup apparatus becomes an important challenge.
Under such situations, in regard to the positional setting method and the dust proof method of an imaging optical system of the image pickup apparatus, various techniques have been proposed. For example, a technique is disclosed in that for eliminating the focus adjustment during manufacturing the image pickup apparatus, an image pickup device and an optical component are positioned in an optical axial direction by making a leg formed integrally with the optical component abut the image pickup device so as to urge the optical component in the image pickup device direction with an elastic member such as a coil spring while measures for dust proof being taken (see Japanese Unexamined Patent Application Publication No. 2003-37758, for example).